Winterizing your RV for Calgary: chinooks, deep cold and freeze-thaw cycles

What makes Calgary winters different for RVs

Chinooks are warm, dry westerly winds that come down off the Rockies and can raise temperatures dramatically in a short time, sometimes melting snow in a day. Then an Arctic air mass slides back in and everything refreezes. For an RV, that means:

• Repeated freeze-thaw cycles. Water left in a low spot (a drain valve, a faucet cartridge, a pump head) freezes, expands, thaws and refreezes again. Each cycle can widen a crack.
• Meltwater on roofs. Snow melts around vents and seams during a chinook and refreezes overnight, which can work water into small gaps in sealant.
• Very dry air. Low humidity dries out rubber seals and sealants.
• Deep cold snaps. Prolonged spells of -25 °C to -30 °C or colder happen most winters, which tests batteries, propane and anything that holds water.

Check current conditions on Environment and Climate Change Canada's weather site before planning winterizing day or a winter trip.

When should Calgary RVers winterize?

There's no fixed date. The Calgary area can see its first hard frosts in September and snow in any month outside summer. A practical approach:

• If you're done camping for the season, winterize before the first forecast hard freeze, and earlier rather than later. Many owners in the Calgary area winterize sometime in late September or October.
• If you want to squeeze in a fall trip, be ready to drain the lines between trips, or travel "dry" with jugs of water and antifreeze in the traps.
• Don't count on a warm forecast. A mild October week can turn quickly.

Full step-by-step instructions are in How to winterize an RV for a Canadian winter (step by step). Below are the parts that matter most for Calgary conditions.

Safety: Use only RV and marine (potable) antifreeze in the fresh water system. Never use automotive antifreeze. Wear eye protection when blowing out lines and keep air pressure modest, following your RV manual.

Air, antifreeze or both?

• Compressed air blows most water out of the lines, but water can remain in low spots, valves and traps.
• RV antifreeze fills those low spots so remaining water can't freeze solid. Check the burst-protection rating printed on the jug.

Given Calgary's deep cold and repeated freeze-thaw, many local owners do both: blow out the lines first, then pump antifreeze through. It costs a few extra jugs of antifreeze and buys real peace of mind. If you use air only, be especially thorough with the low-point drains, the toilet valve, the outdoor shower and the water filter housing.

The spots that crack most often

From experience, these are the usual casualties after a winter:

1. Water pump head, especially if the pump's winterizing bypass was used but the pump itself wasn't run with antifreeze.
2. Outdoor shower valves and the hose connected to them.
3. Low-point drain valves.
4. Toilet water valve and vacuum breaker.
5. Faucet cartridges in kitchen and bathroom taps.
6. City water inlet check valve.
7. Water filter housings left full.
8. Water heater tank if it wasn't drained (a bypassed but undrained tank can still freeze).

Batteries in a Calgary winter

A fully charged lead-acid battery tolerates very low temperatures far better than a discharged one. A flat battery can freeze and crack. Options:

• Remove batteries and store them somewhere above freezing (a heated garage or basement), on a smart maintainer or topped up every month or so.
• Leave them in and on a maintainer if you have power at your storage spot.
• Lithium batteries: Most shouldn't be charged below about 0 °C unless they have built-in heating. Follow the maker's storage advice.

See RV battery not charging: how to troubleshoot the converter and 12V system.

Seals, roof and slides

• Inspect and reseal the roof before the first snow (RV roof maintenance and resealing: a practical inspection and resealing routine).
• Apply a rubber seal conditioner to slide and door seals. Dry Alberta air and cold make rubber brittle.
• Keep slides in for winter unless your manual says otherwise.
• If you store outdoors, plan how you'll safely clear heavy snow from the roof. See RV storage tips for Calgary winters.

Condensation and moisture

When a chinook warms a cold RV, condensation can form inside, especially on windows and in cabinets against outside walls. Use moisture absorbers, leave cabinet doors ajar and check the RV after big temperature swings if you can.

Mid-winter checks

If your RV is accessible, a quick visit every few weeks is worth it:

• Look for roof snow load, ice dams around vents, and water stains inside.
• Check for signs of mice.
• Check battery maintainer status.
• Confirm covers and tarps are secure after windstorms. Calgary's chinook winds can be very strong.

Winter camping instead?

Some Albertans camp all winter. That requires a different approach: heated and enclosed tanks, tank heaters, a heated water hose or travelling with the fresh tank only, skirting, plenty of propane and a reliable battery charging plan. It's very doable, but it's a different project from storage. Make sure your furnace is serviced (RV furnace won't ignite: fan runs but no heat, clicking, or lockout) and your CO and propane alarms work.